The present invention relates to a two-stroke cycle gasoline engine, and, more particularly, to an improvement of idling or low load engine performance of a two-stroke gasoline engine adapted for use with automobiles, when it is operating in a light power output range including idling operation at extremely low output power when compared with standard output power operation.
Ignition rate of fuel-air mixture in idling operation of two-stroke cycle gasoline engines is substantially lower than that of four-stroke cycle gasoline engines, and, because of this, two-stroke cycle gasoline engines have the drawbacks that they generate high noise and vibration and discharge exhaust gases which have high HC content and an offensive odor. When an engine operates in an irregular combustion mode with occasional misfiring and irregular combustion of fuel-air mixture in a cylinder, as a matter of course, the fuel consumption deteriorates. The irregular combustion which occurs in two-stroke cycle gasoline engines is due to insufficient scavenging of the power cylinder, and this is more apt to occur in idling operation in which only a very small amount of scavenging mixture is available.